Kinetics and Mechanism of Leaching Potassium from Biotite in H₂SO₄ Solution

Abstract

Biotite is a potential potassium mineral resource and the dissolution of biotite in H 2 SO 4 solution is a green chemistry approach for recovering potassium. To estimate the efficiency of leaching process and to understand the behavior of leaching reactors, the kinetics and mechanism of leaching potassium from biotite in H 2 SO 4 solution were studied in this work. The leaching experiments show that leached fractions of K 2 O increase with the increasing of temperatures and H 2 SO 4 concentrations, and yet with the decreasing of biotite particle sizes. According to the shrinking core model, the leached fractions of K 2 O were fitted better by diffusion through product layer. A kinetics expression of diffusion-controlled model on three parameters was acquired and it is appropriate to predict the leached fractions of K 2 O from biotite in H 2 SO 4 solution. The dissolution of biotite in H 2 SO 4 solution was interpreted by electrochemical mechanism coupling with characterization of the acid-leached residues. This research results can aid in the design of leaching process for recovering potassium sustainably from biotite.